Neuromuscular and hormonal control of post‐eclosion processes in flies

Abstract

Entomology, Czechoslovak Academy of Sciences, Prague (1. Z.)Flies (exemplified by Sarcophaga bullata) expand after eclosion from the puparium by processes of "pulsing" (slow rhythmical abdominal contractions) and "pumping" of air (fast rhythmical contractions of the cibarial pump). Pulsing and pumping are inhibited if a newly eclosed fly is kept in an enclosed space (sand, a glass tube, an empty puparium). This inhibition no longer applies if such flies are injected with either hemolymph from flies 10-15 min old or CAMP, or are confined at the age of 10 min. This suggests a hormonal control of pulsing and pumping. Pumping alone, without pulsing, occurs in flies treated with certain paralyzing agents like ether, tetrodotoxin, bee venom, or "FlyNap," or have the connectives in the neck cut or interrupted by cauterization. Application of FlyNap or neck cauterization leads to excessive pumping which results in bloating. Expansion by bloating is confined to the soft membranes, leaving sclerites and wings largely unexpanded. The function of pulsing is probably that of "plasticizing" and stretching the cuticle to make it respond to increased steady pressure by airpumping. Flies ligated at the proboscis show almost regular pulsing and pumping, but without intake of air, and consequently no expansion.Cuticle (sclerites) and wings, however, become plasticized. Some plasticization occurs even in the absence, or reduction, of pulsing (in a neck-cauterized fly), brought about by a hormonal process. Eclosion from the puparium is also initiated by a hormonal action. Thus, the following processes during fly emergence are controlled by hormones: eclosion proper, pulsing, pumping, plasticization, and tanning. These hormones are separate entities, with the possible exception of the pulsing/pumping horrnone(s).

Bursicon Functions within theDrosophilaCNS to Modulate Wing Expansion Behavior, Hormone Secretion, and Cell Death

“…Adult ecdysis in winged insects additionally involves the hormonally-mediated deployment of the wings, which are not expanded until this stage. This requires synchronizing physiological changes in the wing cuticle with behaviors designed to increase internal pressure and drive blood into the wings to expand them (Fraenkel et al, 1984). The hardening of the expanded wings marks the end of morphological development and is followed by the remarkable destruction of cells and tissues that support ecdysis (Cottrell, 1962a; Kimura and Truman, 1990; Draizen et al, 1999), a process that is also known to be hormonally dependent (Truman et al, 1992).…”

“…Genetic evidence from Drosophila confirms bursicon's essential role in wing expansion (Dewey et al, 2004), including behavior, in that mutants defective for the bursicon receptor, which is encoded by the rickets gene, do not swallow air or tonically contract their abdomens (Baker and Truman, 2002). These two motor patterns act in concert to force hemolymph into the wings to unfold them (Fraenkel et al, 1984). Whether these behaviors require hormone derived from the bursicon-expressing neurons in the abdominal nervous system or from some other source has remained unknown.…”

curledEncodes the Drosophila Homolog of the Vertebrate Circadian Deadenylase Nocturnin

“…Both aspects of the cu mutant phenotype, i.e., the posterior upwardly bent wings as well as the misorientation of the posterior scutellar bristle, become manifest at expansion phase early after eclosion of the adult fly (File S1). During that stage, flies' behavior follows a stereotypical though environmentally modulated complex motor pattern (Fraenkel et al 1984). The immediate posteclosion behavior is composed of two active motor phases (Baker and Truman 2002) called perch selection phase [phase I according to Peabody et al (2009)] and expansion phase (phase III), which are separated by a largely sedentary interphase (phase II).…”